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arXiv 1608.05441cond-mat.stat-mechcond-mat.soft
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单原子液体中自中间散射函数的V-T理论

V-T theory for the Self-Intermediate Scattering Function in a Monatomic Liquid

Duane C. Wallace, Eric D. Chisolm, Giulia De Lorenzi-Venneri

摘要:

在V-T理论中,原子的运动是在液体特有的势能谷中的谐波振动,加上在众多这样的谷中快速移动系统的凌日。V-T理论首次应用于自中间散射函数(SISF)时,对所有波数q和时间t下的分子动力学(MD)数据进行了精确计算。最近,均方位移(MSD)分析解决了SISF研究中未观察到的交叉行为。我们的目的是将更准确的MSD校准应用于SISF,并评估结果。我们推导并讨论了振动和过境贡献的SISF的理论方程。时间演化被分为三个连续的间隔:振动间隔时,振动的贡献单独准确地占MD数据;交叉时,振动的贡献饱和和过境的贡献变得解决;和扩散的间隔时,过境的贡献单独准确地占MD数据。由此产生的理论误差在所有q和t处都非常小。MSD和SISF的V-T和模式耦合理论的比较表明,虽然它们的公式有很大的不同,但它们的基本原子运动是逻辑对应的。

英文摘要:

In V-T theory the atomic motion is harmonic vibrations in a liquid-specific potential energy valley, plus transits, which move the system rapidly among the multitude of such valleys. In its first application to the self intermediate scattering function (SISF), V-T theory produced an accurate account of molecular dynamics (MD) data at all wave numbers q and time t. Recently, analysis of the mean square displacement (MSD) resolved a crossover behavior that was not observed in the SISF study. Our purpose here is to apply the more accurate MSD calibration to the SISF, and assess the results. We derive and discuss the theoretical equations for vibrational and transit contributions to the SISF. The time evolution is divided into three successive intervals: the vibrational interval when the vibrational contribution alone accurately accounts for the MD data; the crossover when the vibrational contribution saturates and the transit contribution becomes resolved; and the diffusive interval when the transit contribution alone accurately accounts for the MD data. The resulting theoretical error is extremely small at all q and t. Comparison of V-T and mode-coupling theories for the MSD and SISF reveals that, while their formulations differ substantially, their underlying atomic motions are in logical correspondence.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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